Process for the oxychlorination of organic compounds



United States Patent ABSTRACT OF THE DISCLOSURE There is provided aprocess for the oxychlorination of organic compounds wherein a compoundselected from the group consisting of lower alkanes, lower alkenes, and

the partially chlorinated derivatives thereof is contacted in the vaporphase with a chlorinating agent and an oxygen-containing gas in thepresence of an oxychlorination catalyst which is comprised of from 1 toabout 35 percent of a variable valence metal of groups 3-8 of, theperiodic table and from about 65 to 99 percent alumina.

This is a continuation-in-part of SN. 371,775, filed June 1, 1964, nowabandoned.

This invention relates to a novel process for the chlorination oforganic compounds and more specifically relates to the oxychlorinationof organic compounds in the presence of a complex catalyst.

Olefins such as ethylene, propylene, butylene and the like can beoxychlorinated at temperatures of from about 200 degrees centigrade toabout 600 degrees centigrade in the presence of a catalyst comprised ofthe chlorides of metals possessing variable valences. Such processes,however, frequently result in either low yield of product and/or lowpurity of the product. This is because high conversions of startingmaterials to products call for high reaction temperatures which resultin considerable combustion of the starting reactant-s, therebycontributing to loss in yield and contamination of the product.Catalysts normally used for oxychlorinations are often not eitherchemically or mechanically stable in the reaction system, therebyresulting in either a continued decrease in conversion of the startingreactants or the necessity of replacement of the catalyst afterrelatively short operating periods.

In accordance with the present invention there is provided a noveloxychlorination process for the preparation of chlorinated compoundswhich comprises contacting in the vapor phase an organic compound with achlorinating agent and an oxygen-containing gas in the presence of acomplex metal alumina catalyst.

In a specific embodiment of the present invention, there is provided anovel oxychlorination process which comprises reacting':in the vaporphase an organic compound selected from the group consisting of alkanesof from 2 to about 3 carbon atoms, and alkenes of from 2 to about 4carbon atoms, as well as their partially halogenated derivatives, with achlorinating agent and an oxygencontaining gas in the presence of acomplex metal alumina oxychlorination catalyst which is comprised offrom 1 to about 35 percent of a variable valence metal of Group IIIthrough Group VIII of the periodic table coprecipitated with about 65 to99 percent alumina. It is, of course, appreciated that reactantscontaining non-reactive (non-interfering) substituents and possessingsufiicient volatility which will act in the manner described hereincanalso ICC be utilized in the practice of the process of the presentinvention.

Illustrative examples of the alkane reactants which may be utilized inaccomplishing the process of the present invention include ethane andpropane, while examples of alkenes include ethylene, propylene,l-butylene, 2-butylene and isobutylene.

The chlorinating agent utilized can be any agent which will notadversely affect the reaction mechanism, as described herein, such ashydrochloric acid, chlorine, mixtures of chlorine with hydrochloricacid, and the like, while the oxygen-containing gas can be air,substantially pure oxygen and mixtures of either or both together withinert gases such as nitrogen, carbon dioxide, and carbon monoxide, ifdesired.

The preferred catalyst is a porous solid of high mechanical, chemicaland thermal stability under the reaction conditions. The catalyst isused in the form of particles, granules, chips, pellets, and the like,with the granular form being preferred, particularly in the fiuidizingsize previously described. Inert solid diluents, such as carbon orgraphite, can also be mixed therewith if desired.

The copper-alumina complex is prepared in the manner described in US.Patent 1,963,761 by causing alumina hydrate (Al O .3H O) and cupricchloride to coprecipitate in sutficient proportions to result in acatalyst composition containing the desired proportions of copper andalumina. The precipitated complex is filtered from the mother liquor,washed, dried and subsequently roasted at a temperature of about 200degrees centigrade to 400 degrees centigrade. The resulting product is ahard porous material, normally greenish in color, having a specificgravity greater than one. It is physically and chemically durable andhas an indefinitely long operating life. Typically the applicantsprocess can be conducted with said preferred catalyst for from about 12to about 48 months before replacement of the catalyst is required.

Said preferred catalyst is generally prepared by contacting a solutionof alumina hydrate (Al O .3H O) with a variable valence metal halide andhydrochloric acid, thereby causing the coprecipitation of the aluminahydrate and the variable valence metal halide. The alumina hydrate,which is dissolved in a suitable solvent therefor such assodiumhydroxide, may be contacted with a solution of the variablevalence metal halide in hydrochloric acid in order to prepare thecatalyst. Alternatively, both the aluminum hydrate and the variablevalence metal may be dissolved in a suitable solvent, and hydrochloricacid may be added to this solution to cause coprecipitation.

Some suitable solvents which may be used to dissolve the alumina hydrateinclude, for example, alkali metal hydroxides such as sodium hydroxide,potassium hydroxide, lithium hydroxide, calcium hydroxide, and the like.

In place of copper in the preferred catalyst, or in addition thereto,one or more metals of Group III through Group VIII of the periodic tableas shown in Langes Handbook of Chemistry, 8th edition, pages 56 and 57,which possess variable valences, such as scandium, titanium, vanadium,nickel, chromium, cobalt, iron, uranium, silver and gold, can be used asan ingredient in the catalyst. The preferred catalyst, however, iscomprised of a major portion of alumina (A1 0 and a minor but effectiveproportion of copper, the remainder of the catalyst, if any, beingsubstantially inert materials which may be mere impurities. Generally,this complex copper-alumina catalyst contains from about 65 percent to99 percent alumina and from about 1 percent to about 35 percent copperor other metal as described. The preferred range is from about 80percent to 90 percent alumina and about 5 percent to percent copper. Ofcourse, greater and lesser amount of copper and alumina may also beeifective in certain operations.

The other metal complexes, similar to the copperalumina complex, whichare useful as catalysts in the present invention are prepared in thesame manner as the copper-alumina complex. Thus, by precipitatingalumina hydrate in an aqueous solution with a chloride of a variablevalence metal such as by the addition of hydrochloric acid or the like,the variable metal-alumina complex is coprecipitated.

With respect to the molar ratios of the organics, chlorinating agent andoxygen reactants, employed in the invented process, the reaction toproduce chlorinated products will proceed to some extent as long as someof each of the three ingredients is present. In general, however, highconversion of the organics to products is desired and for this result,about 1-150 percent excess of oxygen and about 1 to 80 percent excess ofHCl over the stoichiometric amounts are preferred.

The temperature employed for effecting the process of the presentinvention is generally in the range of 150 to about 350 degreescentigrade and preferably in the range of about 180 to about 250 degreescentigrade. Lower and higher temperatures can be employed, if desired,but the reaction proceeds best in the range mentioned.

The novel process of the present invention is very preferably efiectedin fluidized bed. In the utilization of a fluidized bed, gaseousreactants of varying velocities, usu ally from 2 to centimeters persecond, are caused to proceed from the bottom of the catalyst bed to thetop, said catalyst bed often being a bed of diameter from 2 to 500centimeters and a height of 10 to 300 centimeters, filled wtih finelydivided solid particles containing the complex metal-alumina catalyst.By increasing the velocity of the gaseous reactants, the particles areplaced dynamically in suspension in the rising flow of gases, therebycirculating and otherwise behaving like a fluid, such as a liquid, andestablishing new surfaces of reaction continually. In this respect, itis especially advantageous that the fiuidizing gas is a mixture ofreactants, since thereby the catalyst is utilized most effectively. Thevarious factors to be considered in establishing fluidized beds aredescribed in an article by Wilhelm and Kwauk in Chemical EngineeringProgress, volume 44, page 201.

The process can also be effected, although not as advantageously, in afixed bed where tubular or elongated reactors are used having a highlength/inner diameter ratio. For example, the diameter of the reactormay usually be from about 2 to 10 centimeters, with the length of thereactor being about 2 to 100 times as large as the inner diameter. Thereactors are generally made of soft steel, nickel, or other materialswhich possess a resistance to corrosion by the reactants and products.Also, reactors which have been coated wtih a corrosion resistantmaterial, e.g., ceramic, can be used. There are, of course, heat removaland other problems associated with fixed bed technology, and alleviatedin the case of fluidized beds, that have to be taken into considerationin fixed bed applications.

The term oxychlorination as used throughout the specification, examples,and claims refers to a catalyzed process, wherein the catalyst employedis as described herein, in which a chlorinating agent is contacted withan organic reactant in the presence of an oxygen-containing gas and saidcatalyst. It is believed that in one aspect of this oxychlorinationprocess, the chlorinating agent is produced by the oxidation of hydrogenchloride, which is oxidized to chlorine and water, for example, followedby the reaction of said chlorine with the organic reactant, therebyresulting in the further formation of chlorinated organic compound andhydrogen chloride.

Further, if desired, in another specific aspect of the invention thehydrogen chloride and oxygen containing gas can be added to the catalystinitially in order to amvate said catalyst, followed by reaction withthe organic reactant.

Products produced in accordance with the process of the presentinvention are further purified, if desired, by methods known in this artsuch as washing, distillation and the like.

Aromatic compounds, and their substituted derivatives containing from 6to about 10 carbon atoms, such as benzene, toluene, can also beoxychlorinated in a fluidized bed such as that described herein.

It has been discovered during investigation of oxychlorination processesthat the oxychlorination of acetylene as described herein will result inthe formation of trichloroethylene and/ or perchloroethylene, whichinvention will be the subject of a patent application. Similarly, athird patent application relates to the conversion of organic compounds,such as ethylene, to more highly chlorinated organic compounds such as1,2-dichloroethane by special oxychlorination techniques. Specifically,such invention involves the recycling of unconverted organic reactant.

In order that those skilled in the art may better understand the presentinvention and the manner in which it may be practiced, the followingillustrations and examples are given.

In the specification, examples and claims, parts are by weight andtemperatures are in degrees centigrade, unless otherwise stated.

EXAMPLE 1 In a reactor are placed 50 parts or proportions of thepreviously described complex copper-alumina catalyst of -140 meshparticle size (through 80, on mesh screens). Ethylene at the rate of0.658 molar proportions per hour, anhydrous hydrochloric acid at therate of 1.53 molar proportions per hour and oxygen at the rate of 0.562molar proportions per hour are fed into the reactor, which is maintainedat a temperature of 210 degrees centigrade. The superficial gas velocityduring the reaction was 6 centimeters per second, creating a fluidizedbed. Average contact time was 3.4 seconds. The product was recovered atthe rate of 64.8 grams per hour by cooling the reactor off-gas withwater and then passing the residual gas through a Dry-Ice trap and wasshown by gas chromatographic analysis to be 1,2-dichl0roethane in 96percent pun'ty.

When the catalyst described in Example 5 of U.S. Patent 1,963,761 isused, similarly good results are obtained.

EXAMPLE 2 In a manner similar to Example 1, 50 parts of the catalystutilized in Example 1 were placed in a reactor to form a bed and gaseousreactants were passed through the bed at a superficial velocity of 7centimeters a second, fiuidizing the catalyst bed. The temperature wasmaintained at 330 degrees centigrade and the following reactants wereadded at the rates shown:

Molar proportions/ hr.

1101 gas .67 Air 1.68 1,2-dichloroethane .30

Average contact time in the reactor was 2.8 seconds. The reactor gas waspassed through a water cooled condenser. The product was recovered as inExample 1. It was in 2 phases. The weight of aqueous phase recovered was5.8 parts/hr., while the weight of organic phase recovered was 1182parts per hour. Such yields, although not substantially stoichiometric,were better than those of comparable processes, using other catalysts.

Gas chromatographic analysis of the organic phase gave the followingresults:

EXAMPLE 3 The following reactants were introduced into a fixed reactorbed, comprised of 5 parts of the copper, alumina catalyst as describedin Example 1, and -95 parts of graphite of 6-10 mesh maintained ata'temperature of 285:5 degrees centigrade.

Molar proportions/ hr. Ethylene 1.34 Hydrogen chloride 2.71 Oxygen 1.02Nitrogen 4.08

An average contact time, calculated on the basis of the superficial gasvelocity, was 22 seconds.

The following products were taken 01f:

Molar proportions Ethylene 0.041 1,2-dichloroethane 1.17 Hydrogenchloride .242 Carbon dioxide 0.077 Carbon monoxide 0.077 Water 1.57

While there have been described various embodiments of the invention,the methods and elements described are not intended to be understood aslimiting the scope of the invention, as it is realized that changestherewithin are possible, and it is further intended that each elementrecited in any of the following claims is to be understood as referringto all equivalent elements for accomplishing substantially the sameresults in substantially the same or equivalent manner, it beingintended to cover the invention broadly in whatever form its principlemay be utilized.

What is claimed is:

1. A process for the oxychlorination of organic compounds whichcomprises contacting in the vapor phase at a temperature of from 150degrees centigrade to about 350 degrees centigrade an organic compoundselected from the group consisting of alkanes of from 2 to about 3carbon atoms, alkenes of from 2 to about 4 carbon atoms and theirpartially chlorinated derivatives, with a chlorinating agent selectedfrom the group consisting of hydrogen chloride and mixtures of hydrogenchloride and chlorine and an oxygen-containing gas in the presence of acomplex copper-alumina catalyst prepared by coprecipitating alumina andcopper from a solution of alumina hydrate and copper chloride by theaddition of hydrochloric acid thereto.

2. A process in accordance with claim 1 wherein the reaction is effectedin the presence of a fluidized bed of a co-precipitated complexcopper-alumina catalyst.

3. A process for the oxychlorination of organic compounds whichcomprises contacting in the vapor phase at a temperature of from degreescentigrade to about 350 degrees centigrade an organic compound selectedfrom the group consisting of alkanes of from 2 to about 3 carbon atoms,and alkenes of from 2 to about 4 carbon atoms, and their partiallychlorinated derivatives, with hydrochloric acid and an oxygen-containinggas in the presence of a fluidized bed of a complex co-precipitatedcopper-alumina catalyst comprising as a major active ingredient aluminaand as a minor ingredient combined copper prepared by coprecipitatingalumina and copper from a solution of alumina hydrate and copperchloride by the addition of hydrochloric acid thereto, saidoxychlorination reaction being carried out at a temperature of from 150degrees centigrade to about 350 degrees centigrade.

4. A process in accordance with claim 3 wherein the alkane is ethane.

5. A process in accordance with claim 3 wherein the alkene is ethylene.

6. A process for the preparation of 1,2-dichloroethane which comprisesoxychlorinating in the vapor phase ethylene, an oxygen-containing gas,and hydrochloric acid at a temperature of about to about 250 degreescentigrade and in the presence of a fluidized bed of a complexcopper-alumina catalyst comprised of 65 to about 99 percent of aluminaand from 1 to about 35 percent of combined copper prepared bycoprecipitating alumina and copper from a solution of alumina hydrateand copper chloride by the addition of hydrochloric acid thereto,followed by separation of the product, 1,2-dichloroethane.

7. A process for the oxychlorination of organic compounds whichcomprises contacting in the vapor phase an organic compound selectedfrom the group consisting of alkanes from from two to three carbon atomsand alkenes of from two to about four carbon atoms and their partiallychlorinated derivatives, with a chlorinating agent selected from thegroup consisting of hydrogen chloride, chlorine and mixtures thereof andan oxygen containing gas in the presence of a complex, variable valencemetal-alumina catalyst prepared by coprecipitating alumina and avariable valence metal from a solution of alumina hydrate and a variablevalence metal halide by the addition of hydrochloric acid thereto.

References Cited UNITED STATES PATENTS 1,963,761 6/ 1934 Prahl 260-6502,644,846 7/1953 Johnson et al 260-659 2,783,286 2/1957 Reynolds 260-6592,838,577 6/ 1958 Cook et al. 260-659 2,952,714 9/1960 Milam et a1.260-659 3,042,728 7/1962 Hirsh 260--659 FOREIGN PATENTS 1,304,911 8/1962 France.

LEON ZITVER, Primary Examiner.

T. G. DILLAHUNTY, Assistant Examiner.

US. Cl. X.R.

